The present invention relates to a light guide unit suitable for installation in an instrument, such as a dental handpiece, for transmitting light from a light source to a desired site, a method for producing the light guide unit, and a dental handpiece having the light guide unit installed therein.
A variety of medical or industrial instruments have a lighting system for illuminating a desired site, including a light source and a light guide unit installed in an instrument for transmitting light from the light source to a desired site.
For example, in a conventional dental handpiece with a coupler, a light source such as a halogen lamp is placed in the coupler, and a light guide unit is accommodated in a channel provided through the handpiece for transmitting light from the light source to the head or neck portion of the handpiece. The light thus transmitted through the light guide unit is projected through one or more windows provided in the head or neck portion to illuminate the treatment site.
The channel extends generally axially through the handpiece, and is curved gently with varying cross-sectional shapes. The light guide unit accommodated in the channel is thus required to be deformed to conform to the interior shape of such channel.
An example of such a conventional light guide unit is shown in FIGS. 3(a) and 3(b), designated as light guide unit 30. The light guide unit 30 is composed of a plurality of glass fibers 33, which are bunched together at their ends with metal tubes 31, 32. The bunch of glass fibers may be branched at one end as shown, if desired, and the end of each branch is bunched similarly with a metal tube 31. The metal tubes 31, 32 at the ends of the bunch or the branches are filled with an adhesive to fix the fibers together.
The light guide unit 30 has middle section 35 wherein the glass fibers 33 are not bound together with an adhesive or a metal tube, but are independent from each other. This section 35, on one hand, enables free deformation of the light guide unit 30 to conform to the interior shape of the channel, but on the other hand, the free glass fibers in this section 35 are easily broken and damaged, which causes problems in handling.
It is therefore an object of the present invention to provide a light guide unit that is hard to be broken in handling and that conforms to the interior shape of the channel in which the unit is to be seated.
It is another object of the present invention to provide a method for producing a light guide unit that facilitates production of a light guide unit having sufficient mechanical strength, and that enables easy production of a light guide unit with any configuration in conformity with the interior shape of the channel in which the unit is to be seated.
It is a yet another object of the present invention to provide a dental handpiece having a light guide unit that is hard to be broken in handling.
According to the present invention, there is provided a light guide unit comprising:
a bunch of glass fibers capable of transmitting light from a light source to a desired site,
a sheath of a thermocontracting resin contracted to cover said bunch of glass fibers for substantially its overall length, and
a filler of a hardening resin hardened to fill spaces between said glass fibers within said sheath.
According to the present invention, there is also provided a method for producing a light guide unit comprising a bunch of glass fibers capable of transmitting light from a light source to a desired site, a sheath of a thermocontracting resin contracted to cover said bunch of glass fibers for substantially its overall length, and a filler of a hardening resin hardened to fill spaces between said glass fibers within said sheath, said method comprising:
placing a bunch of glass fibers capable of transmitting light in a sheath of a thermocontracting resin,
filling an interior of said sheath with a filler of a hardening resin so that spaces between said glass fibers are filled with said filler, thereby preparing a sheathed product,
molding a sheathed product in a mold having a desired cavity configuration by applying heat and pressure, and
hardening said filler to fix a configuration of a light guide unit.
According to the present invention, there is further provided a dental handpiece comprising:
a light guide unit for transmitting light from a light source to a treatment site,
a channel for accommodating said light guide unit therein, and
a light projection window in alignment with one end of said light guide unit for projecting light transmitted through the light guide unit onto a treatment site,
wherein said light guide unit further comprises,
a bunch of glass fibers capable of transmitting light from a light source to a treatment site,
a sheath of a thermocontracting resin contracted to cover said bunch of glass fibers for substantially its overall length, and
a filler of a hardening resin hardened to fill spaces between said fiber optics within said sheath.